From patchwork Tue Oct 29 15:21:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vladimir Vdovin X-Patchwork-Id: 13855100 X-Patchwork-Delegate: kuba@kernel.org Received: from qs51p00im-qukt01072702.me.com (qs51p00im-qukt01072702.me.com [17.57.155.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EA48618E028 for ; Tue, 29 Oct 2024 15:22:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=17.57.155.17 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730215352; cv=none; b=X4h2N/Ve0mXsKeTQpRmyyKKUAT4ferLAH1v2fPsyAPHuY6JWqk47EyYqnvzoH9WE+37bSyfTkvLobJ1mNoJHLSNxCv/bxoz4ew2Oot/dswc7ua5dUDPf4OVTECVEGcEsd6dZV85Z4KUvLspDRDR+A1XDUn92P6FfD+Hwyn4HORw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730215352; c=relaxed/simple; bh=YWLiDoGnYiJZnDNDbZ+p+MuIqFLWoZxoaMU15D+xFoQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=aDunn+gtngccgahs/fanx3zXg4qgcm1ggZoBOCq5L6kUHGtKw1g6AgDFPv3BVPN6IIvtjD1ARBMUmrMHJ08gMJ017R3HRKxuP6+qh0bAby7Ma+P4K0pt1A7y0yQHX2DkaPBCgchoNgJtKt6qzEyCuPTX+KENFr7dwq5iEyi9+2A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=verdict.gg; spf=pass smtp.mailfrom=verdict.gg; dkim=pass (2048-bit key) header.d=verdict.gg header.i=@verdict.gg header.b=nUxcXOgC; arc=none smtp.client-ip=17.57.155.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=verdict.gg Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=verdict.gg Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=verdict.gg header.i=@verdict.gg header.b="nUxcXOgC" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=verdict.gg; s=sig1; t=1730215347; bh=9h50V5LS51cfXw+yY9QX3AsgezmwUf5md2Lp3igbiho=; h=From:To:Subject:Date:Message-ID:MIME-Version; b=nUxcXOgCSZUlWpkxzvavswBm9dUNzLyHhkrVXGV8qm4NdGkBXOEbR6BN9RwFpzxua eSypKfCPCl9gjwxtrH0vbEfQciNl5bwXQ+VQc7fwiw2EJ4CCCoEAb+M/5WQBIyK8FT GhKU2Z67heqZHRRMIMjUlYKQ2bQk6qabUag9LTn3JfDqRttPnfvX3T9eIUxBIl82Wf rSxPo/j/sE7DHi1R16WHDTDGeDbQ5Sv8bcvj+yFvWxkB2jdXbPY7VTyadxHl/1XH2n 0k/2rC3Gsve/M4JajdBhspevpD0xrn64f6pORYneHyzH3Q9jhw6y7JnTj69+6rVg2M Fyalx9nukyDqA== Received: from ubuntu-std3-4-8-100gb.. (qs51p00im-dlb-asmtp-mailmevip.me.com [17.57.155.28]) by qs51p00im-qukt01072702.me.com (Postfix) with ESMTPSA id 9029716803C7; Tue, 29 Oct 2024 15:22:25 +0000 (UTC) From: Vladimir Vdovin To: netdev@vger.kernel.org, dsahern@kernel.org, davem@davemloft.net Cc: Vladimir Vdovin Subject: [PATCH] net: ipv4: Cache pmtu for all packet paths if multipath enabled Date: Tue, 29 Oct 2024 15:21:56 +0000 Message-ID: <20241029152206.303004-1-deliran@verdict.gg> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-GUID: hPCm01SqSEUQEN3exmBiLtIg58tRG5mo X-Proofpoint-ORIG-GUID: hPCm01SqSEUQEN3exmBiLtIg58tRG5mo X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1051,Hydra:6.0.680,FMLib:17.12.62.30 definitions=2024-10-29_10,2024-10-29_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 malwarescore=0 mlxlogscore=999 spamscore=0 adultscore=0 phishscore=0 clxscore=1030 suspectscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2308100000 definitions=main-2410290117 X-Patchwork-Delegate: kuba@kernel.org Check number of paths by fib_info_num_path(), and update_or_create_fnhe() for every path. Problem is that pmtu is cached only for the oif that has received icmp message "need to frag", other oifs will still try to use "default" iface mtu. An example topology showing the problem: | host1 +---------+ | dummy0 | 10.179.20.18/32 mtu9000 +---------+ +-----------+----------------+ +---------+ +---------+ | ens17f0 | 10.179.2.141/31 | ens17f1 | 10.179.2.13/31 +---------+ +---------+ | (all here have mtu 9000) | +------+ +------+ | ro1 | 10.179.2.140/31 | ro2 | 10.179.2.12/31 +------+ +------+ | | ---------+------------+-------------------+------ | +-----+ | ro3 | 10.10.10.10 mtu1500 +-----+ | ======================================== some networks ======================================== | +-----+ | eth0| 10.10.30.30 mtu9000 +-----+ | host2 host1 have enabled multipath and sysctl net.ipv4.fib_multipath_hash_policy = 1: default proto static src 10.179.20.18 nexthop via 10.179.2.12 dev ens17f1 weight 1 nexthop via 10.179.2.140 dev ens17f0 weight 1 When host1 tries to do pmtud from 10.179.20.18/32 to host2, host1 receives at ens17f1 iface an icmp packet from ro3 that ro3 mtu=1500. And host1 caches it in nexthop exceptions cache. Problem is that it is cached only for the iface that has received icmp, and there is no way that ro3 will send icmp msg to host1 via another path. Host1 now have this routes to host2: ip r g 10.10.30.30 sport 30000 dport 443 10.10.30.30 via 10.179.2.12 dev ens17f1 src 10.179.20.18 uid 0 cache expires 521sec mtu 1500 ip r g 10.10.30.30 sport 30033 dport 443 10.10.30.30 via 10.179.2.140 dev ens17f0 src 10.179.20.18 uid 0 cache So when host1 tries again to reach host2 with mtu>1500, if packet flow is lucky enough to be hashed with oif=ens17f1 its ok, if oif=ens17f0 it blackholes and still gets icmp msgs from ro3 to ens17f1, until lucky day when ro3 will send it through another flow to ens17f0. Signed-off-by: Vladimir Vdovin --- net/ipv4/route.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) base-commit: 66600fac7a984dea4ae095411f644770b2561ede diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 723ac9181558..8eac6e361388 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1027,10 +1027,23 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) struct fib_nh_common *nhc; fib_select_path(net, &res, fl4, NULL); +#ifdef CONFIG_IP_ROUTE_MULTIPATH + if (fib_info_num_path(res.fi) > 1) { + int nhsel; + + for (nhsel = 0; nhsel < fib_info_num_path(fi); nhsel++) { + nhc = fib_info_nhc(res.fi, nhsel); + update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock, + jiffies + net->ipv4.ip_rt_mtu_expires); + } + goto rcu_unlock; + } +#endif /* CONFIG_IP_ROUTE_MULTIPATH */ nhc = FIB_RES_NHC(res); update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock, jiffies + net->ipv4.ip_rt_mtu_expires); } +rcu_unlock: rcu_read_unlock(); }